Check these links out, Amateur Physics for the Amateur Pool Player by Ron Shepard (pdf file).
http://www.physics.ohio-state.edu/~penningt/262/ps/apapp.pdf
http://www.physics.ohio-state.edu/~penningt/262/ps/apapp.pdf
http://www.jimloy.com/billiard/phys.htm http://www.jimloy.com/billiard/phys.htm